The data management core will provide support for the design and computerization of clinical data collection instruments for patient surveys, concurrent clinical data collection, and retrospective clinical data collection. This core will also provide support for the creation of data collector training manuals, procedures, and programs, for the design and implementation of data quality assurance procedures, and for the assessment of inter-rater reliability. This core will be responsible for creating and managing an independent computer system that facilitates remote linkages to a central server for multiple users and multiple projects. This system maintains secure access to continually-updated project databases, facilitates the remote downloading of data on completed cases and uploading of revisions to instruments and data bases, produces management reports that allow project managers to assess progress of data quality checking and problem solving. Finally, this core will also provide the computer programming capacity to create and analyze research data files from the data collection instruments and databases used in each project. The current members of the Department of Health Policy clinical data collection unit and its data management group have extensive experience in conducting all of these activities. Because all of our proposed projects involve clinical data collection and analysis, centralizing these activities in this core permits uniformly high standards of accuracy to be developed and enforced, allows a single network to be designed that efficiently manages the flow of data, and greatly increases efficiency and reduces overall costs by standardizing proven-effective approaches across all data-related activities, including instrument design, training, data collection, network operation, and data analysis.